1. Field of the Invention
The present invention relates to a sanitary napkin having laterally opposed leakage preventing portions on one side and extensions extending laterally outwardly beyond the leakage preventing portions. More particularly, the present invention relates to a sanitary napkin in which at least parts of the extensions can be folded back against a backsheet and fixed on an undergarment.
2. Description of the Related Art
It is required for sanitary napkins that a menstrual blood can be certainly absorbed by a liquid absorbent layer and never leaks out of the article while wearing. However, the conventional sanitary napkins are liable to deform when applied an external force due to a motion of a wearer. Therefore, if they are deformed in a state where the absorbency cannot be sufficiently exhibited, it is often the case that a menstrual blood will leak and clothing will be stained with the menstrual blood. Especially when the wearer walks, stands up, sits down, or takes exercise, the groin vigorously moves to easily cause a clearance between the worn article and the wearer""s body. Therefore, the discharged liquid flows from the clearance, causing so-called lateral leakage, so that the clothing is stained with the discharged liquid.
Therefore, there has been made a proposal to prevent the lateral leakage in Japanese Unexamined Patent Publication No. H8-280735 (280735/1996) and so on, in which leakage preventing walls are formed on two sides of the article to extend in a longitudinal direction, and wing portions are provided to extend outwardly from the leakage preventing walls. Upon wearing, the wing portions are folded back against the outer side of the crotch portion of the undergarment and fixed on the outer side of the crotch portion through an adhesive layer. On two sides of the article, pocket-like recesses are formed between the leakage preventing walls and the absorbent body. Therefore, even if a menstrual blood is not absorbed by the absorbent body but flows along the topsheet, it can be dammed up by the recesses, thereby preventing the lateral leakage.
In this conventional sanitary napkin, since the article is fixed on the undergarment, the mobility in conjunction with the undergarment can be highly maintained.
In the conventional sanitary napkin, however, it is not always that the wing portions are folded back at the same positions. As a result, the sanitary napkin may possibly be attached to the crotch portion of the undergarment in a rightward or leftward offset position. Particularly when the wearer is in a hurry for changing the sanitary napkin for a new one in fear of stains on clothing, it is often the case that the sanitary napkin is worn without being attached to the undergarment in proper position.
If the sanitary napkin is attached to the crotch portion of the undergarment in a sidewardly offset position, when the wing portions are folded back against the outer side of the crotch portion of the undergarment, there is a strong probability that the root ends of the leakage preventing walls provided on the body-facing side of the sanitary napkin will be positioned at the folds near the root ends of the wing portions. If the root ends of the leakage preventing walls are positioned at the folds, the leakage preventing walls near the edges of the crotch portion of the undergarment are liable to deform, thereby deforming the pocket-like recesses.
In addition, if a sideward pressure is applied to the crotch portion of the undergarment due to compression by the thighs, such pressure directly acts on the root ends of the leakage preventing walls, which are positioned near the edges of the crotch portion of the undergarment. Therefore, the leakage preventing walls are liable to deform, causing a clearance between the leakage preventing walls and the wearer""s skin. Moreover, the pocket-like recesses are also liable to deform, deteriorating the effect of preventing the liquid leakage.
The present invention has been worked out in view of the shortcoming in the prior art set forth above. It is therefore an object of the present invention to provide a sanitary napkin, which assures that when at least parts of extensions are folded back against an outer side of an undergarment, folds can be certainly spaced apart from root ends of leakage preventing portions and a sidewardly applied force can be relieved by a region between the fold and the leakage preventing portion, thereby preventing deformation of the leakage preventing portions and increasing the effect of preventing lateral leakage.
According to the invention, there is provided a sanitary napkin having extensions, at least parts of which are to be folded back and fixed on an undergarment in use, the sanitary napkin comprising:
a liquid-permeable topsheet disposed on one side of the sanitary napkin to cover at least a central region thereof;
a backsheet;
an absorbent layer disposed between the topsheet and the backsheet; and
leakage preventing portions disposed on laterally opposed side portions of the topsheet and extending in a longitudinal direction of the sanitary napkin, joints between the respective leakage preventing portions and the topsheet being formed to extend in the longitudinal direction, the extensions being portions of the sanitary napkin extending laterally outwardly beyond the joints, wherein
each extension includes: a flexible region for facilitating folding thereof, which is spaced laterally outwardly apart from corresponding one of the joints: and a buffer region of a predetermined width between the flexible region and the corresponding joint, a compression energy of the buffer region in a thickness direction thereof being in a range of 0.4 to 1.0 (Nxc2x7m/m2).
In the sanitary napkin, the buffer region is provided between the flexible region and the corresponding joint and the compression energy of the buffer region is set within the foregoing range. Therefore, a sidewardly applied pressure is relieved by the buffer region and hardly acts on the joint directly, thereby preventing deformation of the leakage preventing portion.
Preferably, a nonhydrophilic sheet is provided such that one portion thereof forms the leakage preventing portion and another portion thereof forms one surface of the extension, at least one intermediate sheet is disposed in the buffer region to be positioned between the backsheet and the extension surface-forming portion of the nonhydrophilic sheet, and the flexible region extends outwardly from an outwardly directed edge of the intermediate sheet. In the case where the buffer region is constructed to have at least three sheets, as set forth above, the compression energy of the buffer region can be easily set within the foregoing range.
Preferably, the intermediate sheet is not bonded to either overlying or underlying sheets. In this case, when a pressure is sidewardly applied to the buffer region, a clearance can be formed between the sheets, thereby increasing the ability of relieving the pressure.
It is also preferred that a portion of the leakage preventing portion-forming portion of the nonhydrophilic sheet is extended outwardly beyond the joint to form the intermediate sheet and/or that a portion of the topsheet is extended outwardly beyond the joint to form the intermediate sheet. In the case where the intermediate sheet is formed of the nonhydrophilic sheet or the topsheet, it is not required to separately provide the buffer region with another sheet for buffering, there by making the structure simple.
Preferably, the leakage preventing portion includes an elastic member for exhibiting an elastic contractive force in the longitudinal direction, and the leakage preventing portion is allowed to rise away from the topsheet while having the joint as a root end thereof. In this case, a liquid flowing along the topsheet can be certainly dammed up by the leakage preventing portion.